Remote Connection over the Internet

[omara007]

Hi Folks

I want to remotely connect to my CentOS 4.6 linux over the internet. The CentOS is installed on my laptop at home and I'm trying to reach it from work. The first problem I'm facing is that I can't even ping my home machine !! .. it looks like the IP that I'm using at home is not a real one. I tried using "IP Address Locator" and amazingly I found that both work and home machines have one real IP (both home and work connection are from the same exact ISP).

I'm completely clueless regarding what should be done to access my home linux .. anyone has an advice ?

[Dapper Dan]

Hi omara007 and welcome! You didn't say whether it was a Linux machine you were using to connect to your home box with or a Windows or Mac machine. If Linux, then it's a matter of using ssh to get into your homebox...

ssh homebox@its_ip_add_ress

In Windows, you can use "putty." Bring up a terminal after it is installed and do the same thing. To find your home box's ip. get on it and into a web browser and input into the address window:
whatismyip.com
If you are using a router, you'll need to forward the correct ports to the laptop's home network ip.

[omara007]

Hi omara007 and welcome! You didn't say whether it was a Linux machine you were using to connect to your home box with or a Windows or Mac machine. If Linux, then it's a matter of using ssh to get into your homebox...

ssh homebox@its_ip_add_ress

In Windows, you can use "putty." Bring up a terminal after it is installed and do the same thing. To find your home box's ip. get on it and into a web browser and input into the address window:
whatismyip.com
If you are using a router, you'll need to forward the correct ports to the laptop's home network ip.

Hi Dapper ..

Seems you didn't get me correct .. the main problem is that I can't even ping my home linux from anywhere .. it's even a step before choosing the remote connection tool to be used .. and I know there are many .. starting from telnet, to ssh and VNC ..

Let me clarify more about the problem ..

1. I have a DSL modem .. and this modem is connected to a Wireless Router .. the modem is always up and connected ..
2. My laptop is a dual boot : CentOS 4.6 and WinXP.
3. Whether I'm on linux or windows .. I should be having the same IP as I don't disconnect my modem.
4. When I query my IP from windows using : ipconfig /all .. I get a specific IP .. let's say it's : 81.99.82.123
5. I'm a subscriber of a certain ISP here in Dubai .. it's called Etisalat .. and all of my neighbors in the building are also subscribers of the same ISP.
6. I asked one of my neighbors to ping me .. using that IP i got from ipconfig .. my neighbor tried to ping but he faild ..
7. I tried to ping his IP but I failed as well !!!
8. I then looked at "whatismyip" website and I found my real IP is different from the one that ipconfig prompted me .. so, I concluded that "81.99.82.123" is a virtual to my ISP.
9. If i'm able to ping my IP from outside, I guess the next step of chosing ssh or VNC will be easy .. but now, I don't know why I can't even ping my home machine !!


Did I manage to make myself clear ?

[Dapper Dan]

Did I manage to make myself clear ?

Clearer yes...
How many machines are being served by your router? Is it possible that you and your neighbor's IP's (the one's you get when doing ipconfig) are the LAN IPs assigned to these machines by the router(s)? Some routers have configurations for ignoring ping, check for that too. You might want to also contact your ISP and tell them your situation and see if they can shed some light on it. It's very possible your ISP is blocking ping. Regardless of ping, I'd still try to reach the CentOS laptop from outside the LAN using ssh. Make sure port 22 is forwarded (in your router) to the CentOS laptop and try contacting it from outside using the ip that "whatismyip" gave you.

[omara007]

Clearer yes...
How many machines are being served by your router? Is it possible that you and your neighbor's IP's (the one's you get when doing ipconfig) are the LAN IPs assigned to these machines by the router(s)? Some routers have configurations for ignoring ping, check for that too. You might want to also contact your ISP and tell them your situation and see if they can shed some light on it. It's very possible your ISP is blocking ping. Regardless of ping, I'd still try to reach the CentOS laptop from outside the LAN using ssh. Make sure port 22 is forwarded (in your router) to the CentOS laptop and try contacting it from outside using the ip that "whatismyip" gave you.

1. Me and my neighbor are not using the same router. I do have a personal wireless router at home. He is using a completely different internet account but still from the same ISP.
2. I used Whatismyip and I (as said before) got a different iP than the one shows when running (ipconfig /all). Unfortunately, both IPs are not pingable. So, you can be true in that the ISP might be blocking the ping.
3. I tried doing ssh on the IP regardless of the ping thing but still I can't reach the linux PC !!
4. Someone told me that I should find something like LogMeIn but for Linux. Do you have any idea how can something like this help me ?

[Dapper Dan]

1. Me and my neighbor are not using the same router. I do have a personal wireless router at home. He is using a completely different internet account but still from the same ISP.

You do not have to be on the same router to get internal IPs from either of them. His router can give him an IP within his LAN and your router can give you one on yours. As an example, here's my setup:

My IP from my ISP is not the same as the IP given to my computer within my home network. The IP from my ISP is to my modem. After that, each computer on my network has a different IP assigned to it by the router. My main machine is assigned 192.168.1.1. My wife's is 192.168.1.2. My Children's is 192.168.1.3 and so on. If I am outside my network, (on a friend's computer across town), and I want to ssh into my home computer, I ssh the IP given me by the ISP. This will be the same as the IP you see when doing "whatismyip." In my router, port 22 is forwarded to my home box's internal IP - 192.168.1.1

In your router's configuration utility, look under "port forwarding." Configure it so port 22 is forwarded to your CentOS's IP assigned to it by your router. You can find this by opening a terminal and doing:

/sbin/ifconfig

Another thing you need to check for is to see if your CentOS machine has port 22 open, otherwise it will be refused. Open a terminal and do:

system-config-firewall

It might possibly be:

system-config-securitylevel

(As it was changed at some point and I can't remember when). At any rate, this opens up your firewall configuration utility in CentOS. Make sure that port 22 is open. If you do all of these things, your ssh request will have clear passage straight to your CentOS laptop IF the ssh server is running on the laptop. I'm almost certain CentOS has sshd set to start up automatically at boot so that should not be the problem.

How to make it all work:

Let's say for instance that /sbin/ifconfig shows your CentOSs LAN IP to be 192.168.0.1. In your router, you will forward port 22 to that address. That's because port 22 is the default port ssh uses. Lets say your IP assigned to your modem from your ISP is 123.456.7.100. Let's further assume for example's sake that your CentOS username is "omara007." From outside your network (across town at your girlfriends computer for instance) you would open a terminal on her Linux machine, or open a Putty terminal on a Windows machine and do:

ssh omara007@123.456.7.100

Unless your ISP or router is blocking port 22, you would wait a few seconds and then reach your modem and router. Your router then routes your ssh request through port 22 to your CentOS machine on 192.168.0.1 - the CentOS laptop.

Someone told me that I should find something like LogMeIn but for Linux. Do you have any idea how can something like this help me ?

Unless something has changed, I don't think there is a version of LogMeIn for Linux, only Windows. You can use this service from a Linux machine's browser to a Windows machine but not the other way round. Are you wanting to "see" this CentOS machine's desktop? If that is the case, then you'd want to use VNC or Nomachine which is a whole different process. ssh merely gives you a reasonably secure connection so you can view, manipulate, run commands and transfer files from the command line which is vitally useful on Linux machines.

[omara007]

First .. I'm not talking about the internal IP that the router gives me .. at all .. in other words, all the IPs I have mentioned are not local to my home LAN .. whether the one I got from ipconfig /all or the one I got from "whatismyip" ..

I will try what you said in the rest of your reply and let you know once done .. thanks in advance

[sarikamanepalli]

Hi Frnds,
I am trying to implement Mobile IP on linux PCs. I need information regarding the tunnel, the HA and FA are sending the advertisements but when moved to FA, MN is unable to communicate with FA/HA. I am using Dynamic Mobile IP as Mobile IP client.